Chapter 14 – The Ocean Floor

14.1 The Vast World Ocean

Text pp 394-400

The Blue Planet • Nearly 71% of Earth’s

surface is covered by the global ocean.

Oceanography is the science that studies the global ocean, and draws on geology, chemistry, physics and biology.

Geography of the Oceans • About 360 million square kilometers, or 71%,

of all the surface of Earth is represented by oceans and smaller seas, such as the Caribbean Sea.

• The world ocean can be divided into four main ocean basins – the Pacific Ocean…

•Largest ocean, and the largest single geographic feature on Earth. •Covers half the ocean surface. •World’s deepest ocean.

• …the Atlantic Ocean…

•Half the size of the Pacific Ocean. •Not quite as deep as the Pacific. •Relatively narrow in width.

• … the Indian Ocean…

•Slightly smaller than the Atlantic. •Just as deep as the Atlantic. •Located almost entirely in the Southern Hemisphere.

• … and the Arctic Ocean.

•About 7% the size of the Pacific Ocean •A little more than ¼ deep as the rest of the oceans.

Mapping the Ocean Floor

• The topography of the ocean floor is as diverse as that of the continents.

• We would see volcanoes, tall mountain ranges and large submarine plateaus if we could see to the bottom.

• Bathymetry (bathos = depth, metry = measurement) is the measurement of ocean depths and the charting of the shape or topography of the ocean floor.

• Today’s technology – particularly sonar, satellites, and submersibles – allows scientists to study the ocean floor in a more efficient and precise manner than ever before.

SONAR • SONAR stands for…

• SOund

• NAvigation and

• Ranging

SONAR works by transmitting sound waves toward the ocean bottom, and a receiver intercepts the echo reflected upwards.

• Depth can be calculated from the speed of sound waves in water, and the time required from the energy pulse to reach the ocean floor and return. In this way a profile of the ocean floor is created.

Satellites • Measuring the shape of the ocean floor from

space is another recent technological breakthrough. Satellites can give us extremely accurate measurements, using microwaves instead of sound waves.

Submersibles

• A submersible is a small underwater craft used for deep-sea research. Submersibles are used to collect data about areas of the ocean that were previously unreachable by humans.

• Today, many submersibles are unmanned and operated remotely by computers.

These remotely operated vehicles (ROVs) can remain under water for long periods.